As this is a cleptoparasitic species, all flower visits will be for nectar only. Westrich (1989) lists the following plant species as nectar sources: Salix (Salicaceae); Taraxacum officinale (Asteraceae); Frangula alnus (Rhamnaceae); Jasione montana (Campanulaceae); Succisa pratensis (Dipsacaceae).
Smit et al. (2004) citing others lists Hieracium sp., Taraxacum officinale (Asteraceae) and Salix repens (Salicaceae) as nectar sources in the Netherlands